1. Field of the Invention
The invention is directed to a process for cutting panels, or the like, from a wood fiber board which is provided, in particular, with a decorative layer basically consisting of paper, where the length and/or width value of the decorative layer deviates from its original value after it is applied to the wood fiber board, which process employs a board-dividing apparatus exhibiting at least one saw, where the saw is formed by a plurality of saw blades which are adjustably spaced in parallel fashion.
2. Background Description
Panels are employed in, e.g., flooring, particularly laminate flooring. The desired decoration (parquet, wood graining, floor tiles, etc.) is printed on a paper web, which is then coated with artificial resin and rolled onto a roller. The decorative web thus prepared is then applied to the wood fiber boards at the floor manufacturer. With the printing of the decoration onto the paper web, the later sealing of the paper web with artificial resin, and the subsequent attachment of the decorative layer by means of pressure and temperature to the wood fiber board, the dimensions of the paper are modified. The paper grows both in length (lengthwise growth) and width (widthwise growth). If this decorative board is only to be cut into individual panels, the growth in length and width must be taken into account, since otherwise there will be a non-uniform distribution of the decoration on the individual panels. The result of this would be that the floor composed of an unevenly distributed decorative layer would exhibit gaps in the decoration on the connecting rims of the panels. Even if these gaps amount to only a few millimeters, they are noticeable upon closer observation, and this has a negative aesthetic effect and thus diminishes the quality of the laid-out floor.
In order to manufacture according to quality standards, the paper growth must be ascertained and the saw adjusted accordingly. Since this occurs manually, the process is very time-consuming and therefore cost-intensive. If the dimensions are not correctly determined, the danger of immediately producing rejects is high. Particularly when joined tiles are printed as decoration, slight discrepancies in individual panels are noticeable at the joint abutments. A discrepancy of only 2 mm is unacceptable since this could entail the complete displacement of the joint. Thus the saw must be permanently reset, which highly increases the cost of the panels.
According to the invention an automated cutting process with the paper growth taken into account is performed using the following steps:
the wood fiber board is aligned with at least one initial camera;
a defined, predetermined point in the decorative layer is recorded by each of the first camera and a second camera;
the distance between the points is determined;
the discrepancy in the width or length value is determined by comparison of the actual position and the desired position of the points;
the value of the determined discrepancy A is placed in relation to the number n of the saw blades;
the parallel spacing of the saw blades is modified by the value of the ratio of the discrepancy to the number of saw blades A/n;
the orientation of the wood fiber board to the saw is displaced to one side in the amount of one half the determined discrepancy; and then
the wood fiber board is transported toward the saw for cutting out the panels.
Instead of setting the value of the determined discrepancy into relation with the number of saw blades and then adjusting the parallel distance accordingly, as an alternative it is possible to set the determined distance between the points (actual value) into relation with the number of saw blades and then to adjust the parallel spacing between the saw blades to the value of the ratio of the distance to the number of saw blades (L/n).
With this process, it is possible to automatically record or determine the paper growth and, with the resulting data, to adjust the saw and to position the wood board in front of the saw, without the need for conceptual activity, which is fundamentally subject to risk of error. Since a reproducible adjustment is made again and again, the quality of the sawed panels is very high. Even difficult decorations, e.g., file decorations, can be processed with a high level of quality and in a cost-effective way.
If another defined point is recorded with a third camera and the actual position of the points is again compared with the desired position of the points, the growth in the other direction can simultaneously be determined. In keeping with the determined data, both the longitudinal saw and the transverse saw are adjusted, and the wood board is moved in one direction by half the amount of the offset from the saw; here the offset, i.e., the growth in length and width, do not have to be identical, and the overall result is that even a complicated behavior can be controlled. Instead of identifying defined points in the decorative layer with the camera, it is also possible to apply markings to the edge of the paper web, markings which can be detected by the cameras. With this measure it is possible to apply the process according to the invention even when a low-contrast decoration is involved.
Ideally the determined discrepancy will be stored with an added amount for tolerance. Other boards that follow the first board, which was measured in the manner described above, are brought into line with the first camera, and the discrepancy in the width and/or length value is then determined. The discrepancy thus determined is compared with the total of the discrepancy of the first board less the tolerance addition, and only if the discrepancy of the later board is greater than that of the first board less the tolerance range will there be a new adjustment of the saw blades and a new repositioning of the wood fiber board by half the amount of the discrepancy or, as the case may be, only then will the saw be moved up by the corresponding amount.
With this measure it is possible to individually adjust the tolerance to the given decoration, which permits production to be immediately adjusted to the demanded or accepted standard of quality. Thus, in a tile decoration it will be necessary to select a fundamentally smaller tolerance range than is the case with a grooved floor decoration or a veneer decoration. The saw blades can be positioned on a common shaft. It is also possible to form the saw from individually driven saw blades, whose distance from each other is adjustable.